[bojan]

While waiting for parts for 400D to arrive, I started to work on 450D.
This camera was described on ebay as faulty, with SD card reader problem

After dismantling, it became obvious what was wrong - it seems camera was splashed with sea water (most likely.. I also found inside a lot of sand particles clinging on exposed edges of sticky tapes... luckily the shutter is OK), some of it came between battery compartment and SD card reader (SD card door was also hard to move and diopter button next to optical viewer was completely clogged with brown rusty substance).. and couple of tracks on PCB were eaten away, starting from inside plated via hole (obviously, the quality of PCB manufacture was not brilliant, as via were not tinted properly).
Anyway.. against everything I know about best professional repair practices, I decided to fix this particular board, as it didn't look damaged beyond repair.
One of the data lines was easy - since the copper inside via was completely turned into green crystalline (and non-conductive) stuff, I cleaned the hole with 0.3mm diameter steel wire and then simply inserted and soldered a strand of plated copper wire (from IDC cable) on both sides.

The other two damaged via were more difficult - they went from bottom side of the board to top side, but under the SD card slot. So I decided to remove it to see where the tracks are ending (the slot was also slightly corroded, so I was thinking, it is not a big deal if I damage it in the process, especially because they are available on ebay for ~$5 each). However, after removal it was left in a pretty good shape and useable... but I will still replace it with new one.

This kind of work can not possibly be done without good stereo microscope (20~30x)... Good soldering iron is also important (I have Weller, magnastat, with sharp tip #7)... and steady hand of course.